/Engine/Plugins/Enterprise/DatasmithImporter/Source/ExternalSource/Public/ExternalSource.h
Return the DatasmithScene if it is loaded, return an invalidTSharedPtrotherwise.
[TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [IDatasmithScene](API\Runtime\DatasmithCore\IDatasmithScene) > GetDatasmithScene() const